I AO 10: Principles of Programming Languages
Introduction and course organization
Achim Blumensath blumens@fi.muni.cz Faculty of Informatics, Masaryk University, Brno
Warm-up: A Quiz
What does this program do?
++++++++++ [ >+++++++>++++++++++>+++>+«« - ] >++. >+. +++++++ . . +++. >++.«+++++++++++++++. >. +++.------.--------.>+.>.
Warm-up: A Quiz
What does this program do?
++++++++++[>+++++++>++++++++++>+++>+««- ] >++. >+. +++++++ . . +++. >++.«+++++++++++++++. >. +++.------.--------.>+.>.
Prints "Hello World!"
Warm-up: A Quiz
What does this program do?
++++++++++[
-]>++.>+.+++++++
..+++.>++.
Prints "Hello World!"
Brainfuck (1993)
• Turing-complete programming language
• tape containing numbers (inc/dec), a data pointer (1/r), input/output, conditional jump
• compiler of size 100 bytes known to exist
(moreinfo: http://en.wikipedia.org/wiki/Brainf uck)
Before high-level programming languages ...
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Now...
C Python Haskell Scala
C++ PHP OCaml Rust
Java JavaScript F# Go
C# VisualBasic Scheme Swift
Ada Perl
Now...
c	Python	Haskell	Scala
c++	PHP	OCaml	Rust
Java	JavaScript	F#	Go
c#	VisualBasic	Scheme	Swift
Ada	Perl	•  • •	
A zoo of programming languages
Now...
c	Python	Haskell	Scala
c++	PHP	OCaml	Rust
Java	JavaScript	F#	Go
c#	VisualBasic	Scheme	Swift
Ada	Perl	•  • •	
A zoo of programming languages
Can we somehow categorise them ? How do we choose one?
Profanity is the one language all programmers know best.
Anon.
PL popularity
TIOBE index, January 2017, www. tiobe. com
J;iii 2017	Jan 2016	Change	Programming Language	Ratings	Change
1	1		Java	17,278%	-4.19%
I	2		C	9.349%	■6.69%
3	3		C++	6.301%	-0.61%
1	1		c*	4.039%	-0.67%
5	5		Python	3.465%	-0.39%
6	7		Visual Basic .NET	2.960%	1-0.38%
7	8		JavaScript	2.850%	+0.29%
8	1 1		Perl	2.750%	+0.91%
9	9		Assembly language	2.701%	+0.61%
H)	6		PHP	2.564%	-fl.MW
11	L2	A	Delphi/Object Pascal	2.561%	+0.78%
12	10	V	Ruby	2.546%	+0.50%
13	54		Go	2.325%	+2.16%
14	14		Swift	1.932%	+0.57%
1 C	11		\n----1 n—1 —	1 ; > t --ill'	
PL popularity
TIOBE Programming Community Index
Source: www.tiobe.com
30
2002 2004 2006 2008 2010 2012 2014 2016
Desirable language features
Desirable language features
simplicity
orthogonality
clear (and defined) semantics
ease of use
easy to learn
clean and readable syntax
expressive power
support for many paradigms and coding styles
strong safety guarantees
produces fast code
compilation speed
reduced memory usage
good library and tool chain support
standardisation and documentation
interoperability with other languages
hardware and system independence
support for hardware and system programming
Coding style choices
Coding style choices
• readability: the code is easy to understand
• reliability: the program does what it is supposed to
• maintainability: it is easy to fix bugs and add new features
• efficiency: the program runs fast
Programming paradigms
Programming paradigms
• procedural: program is structured as a collection of procedures/functions
• imperative: list of commands
• functional: expressions that compute a value
• declarative: describe what you want to compute, not how
• object-oriented: objects communicating via messages
• data-oriented: layout of your data in memory
• reactive: network of components that react to events
Programming paradigms
• procedural: program is structured as a collection of procedures/functions
• imperative: list of commands
• functional: expressions that compute a value
• declarative: describe what you want to compute, not how
• object-oriented: objects communicating via messages
• data-oriented: layout of your data in memory
• reactive: network of components that react to events
Which one to use ?
Programming paradigms
procedural: program is structured as a collection of procedures/functions
imperative: list of commands
functional: expressions that compute a value
declarative: describe what you want to compute, not how
object-oriented: objects communicating via messages
data-oriented: layout of your data in memory
reactive: network of components that react to events
Which one to use ?
Choose the right tools for the job!
Programming paradigms
• procedural: program is structured as a collection of procedures/functions
• imperative: list of commands
• functional: expressions that compute a value
• declarative: describe what you want to compute, not how
• object-oriented: objects communicating via messages
• data-oriented: layout of your data in memory
• reactive: network of components that react to events
Which one to use ?
Choose the right tools for the job!
Multi-paradigm languages
The more paradigms your language support, the more tools you have in your toolbox.
Why study programming languages and
paradigms ?
The study of language features and programming styles helps you to
• choose a language most appropriate for a given task;
• think about problems in new ways;
• learn new ways to express your ideas and structure your code (=> more tools in your toolbox);
• read other peoples code;
• learn new languages faster (you only need to learn a new syntax);
• understand the design/implementation decisions and limitations of a given language, so you can use it better:
• You can choose between alternative ways of expressing things.
• You understand more obscure features.
• You can simulate features not available in this particular language.
Aspects of programming languages
Syntax - the structure of programs.
Describes how the various constructs (statements, expressions,...) can be combined into well-formed programs.
Semantics - the meaning of programs.
Tells us what behaviour we can expect from a program.
Pragmatics - the use of programming languages.
In which way is the language intended to be used in practice? What are the various language constructions good for?
Aspects of programming languages
Syntax - the structure of programs.
Describes how the various constructs (statements, expressions,...) can be combined into well-formed programs.
PA008 Compiler Construction, IB005/IA006 Formal Languages
Semantics - the meaning of programs.
Tells us what behaviour we can expect from a program.
IA Oil Programming Language Semantics
Pragmatics - the use of programming languages.
In which way is the language intended to be used in practice? What are the various language constructions good for? This course!
Course organisation
Lectures
• Thursday, 10:00, A318
• language: English
• video recordings will be available on IS
• some slides and lecture notes (in progress) will also be made available
Examination
• final written exam
• in English
• k and z completion possible
Prerequisites
• no formal requirements
• knowledge of at least one of C/C++/Java
• knowledge of at least one functional language (Haskell,
• knowledge of object-oriented programming (OOP)
• the more languages you know the better ©
Study materials
Course information, additional resources
• https://is.muni.cz/auth/el/1433/jaro2016/IA010/ index.qwarp
• Rosettacode rosettacode.org Books
• P. V. Roy, S. Haridi, Concepts, Techniques, and Models of Computer Programming, ist ed., MIT Press, 2004.
• R. W. Sebesta, Concepts of Programming Languages, 10th ed., Addison-Wesley, 2012.
• Programming language pragmatics, (Ed. M. L. Scott) 3rd ed. Oxford, Elsevier Science, 2009.
Topics covered
• brief history of programming languages
• names, bindings, scope
• types, type checking, type inference
• data abstraction: abstract data types
• control flow
• subprograms (functions, methods,...)
• exceptions
• object-oriented programming
• concurrency
• functional programming